Generate exports field in package.json

fix-exports.js

import fastGlob from 'fast-glob';
import { promises as fsp } from 'node:fs';
import { createRequire } from 'node:module';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
import { parseArgs } from 'node:util';

const _require = createRequire(fileURLToPath(import.meta.url));

async function generateExports(packageName, force) {
  const exports = {};
  const root = path.dirname(_require.resolve(packageName));
  const files = await fastGlob(path.join(root, '**/package.json'), {
    ignore: [path.join(root, 'node_modules')],
    absolute: true,
  });

  for (const file of files) {
    const { default: pkg } = await import(file, { with: { type: 'json' } });
    const dirPath = path.dirname(file);

    const exportKey = pkg.name.replace(packageName, '.');

    const pkgEntry = `./${path.relative(root, file)}`;
    const importEntry = path.resolve(dirPath, pkg.module);
    const requireEntry = path.resolve(dirPath, pkg.main);
    const typesEntry = path.resolve(dirPath, pkg.types);

    exports[exportKey] = {
      import: `./${path.relative(root, importEntry)}`,
      require: `./${path.relative(root, requireEntry)}`,
      types: `./${path.relative(root, typesEntry)}`,
    };
    exports[pkgEntry] = pkgEntry;
  }

  const rootPkgPath = path.resolve(root, 'package.json');
  const { default: rootPkg } = await import(rootPkgPath, { with: { type: 'json' } });

  if (!rootPkg.exports || force) {
    rootPkg.exports = exports;
    await fsp.writeFile(rootPkgPath, JSON.stringify(rootPkg, null, 2), 'utf-8');

    console.log(`[success] The field "exports" in "${packageName}" successfully patched!`);
  } else {
    console.log(`[skipped] The field "exports" in "${packageName}" already exists!`);
  }

  return exports;
}

async function run() {
  const args = process.argv.slice(2);
  const parsed = parseArgs({
    args,
    options: {
      packages: { type: 'string', short: 'p' },
      force: { type: 'boolean', short: 'f' },
    },
  });
  const packages = parsed.values.packages?.split(',') ?? [];

  for (const name of packages) {
    await generateExports(name, parsed.values.force);
  }
}

run();

Usage:

node fix-exports.js -p @apollo/client